This section provides background information related to the present disclosure which is not necessarily prior art.
Selective catalytic reduction technology has been used in conjunction with reducing nitrogen oxides present in the exhaust of combustion engines. Many vehicles utilizing combustion engines are equipped with exhaust aftertreatment devices for reducing nitrogen oxide emissions. Some of these systems include a reductant delivery system for transmitting the reductant (e.g., urea or gaseous ammonia) from a tank to the exhaust stream. A mixer may be provided for mixing the injected reductant with the exhaust gas before the reductant reaches a catalyst with which the reductant reacts.
Some mixers may include structures with relatively sharp edges that include a surface roughness as a result of manufacturing. The geometry, including sharp edges, of the known mixers may result in wall film formation which increases the time required to atomize injected reductant. Wall film formation may also lead to urea deposits being formed on the mixer or on an interior wall surface of a conduit in which the mixer is positioned. While these systems may have performed well in the past, it may be desirable to provide an improved mixing system that is able to reduce wall film formation to more efficiently and effectively mix the reductant with the exhaust stream before the mixture reaches a catalyst.